define 5D object with memory allocation - c

Question

I need to clear memory of 5D object, so first I need to define it with memory allocation.
My previous object definition was:
double I_object[N_GROUPS][NN][NN][NN][NN]={0};
I replaced it by code below and c file compiles but c program crashes :(
I_object=(double *****) malloc(sizeof(double *****)*N_GROUPS);
for(i = 0; i < N_GROUPS; i++){
I_object[i]=(double ****) malloc(sizeof(double****)*NN);
for(j = 0; j < NN; j++){
I_object[i][j]=(double ***) malloc(sizeof(double***)*NN);
for(k = 0; k < NN; k++){
I_object[i][j][k]=(double **) malloc(sizeof(double**)*NN);
for(l = 0; l < NN; l++){
I_object[i][j][k][l]=(double *) malloc(sizeof(double*)*NN);
}
}
}
}
Please let me know if this 5D object definition is wrong or where I can find how to define 5D object using malloc.

Answer 1

You forgot to declare the type of I_object. Also, you need to declare i, j, k and l. Also, I wouldn't cast the result of malloc in C. Furthermore, the indirection levels are wrong in your sizeof() calls, which causes a problem in the last one, where there might be a difference between the sizes of a double and a double*.
With those changes, it looks like this:
#define N_GROUPS 3
#define NN 3
int main() {
double *****I_object = malloc(sizeof(double ****)*N_GROUPS);
for (size_t i = 0; i < N_GROUPS; i++) {
I_object[i] = malloc(sizeof(double***)*NN);
for (size_t j = 0; j < NN; j++) {
I_object[i][j] = malloc(sizeof(double**)*NN);
for (size_t k = 0; k < NN; k++) {
I_object[i][j][k] = malloc(sizeof(double*)*NN);
for (size_t l = 0; l < NN; l++) {
I_object[i][j][k][l] = malloc(sizeof(double)*NN);
}
}
}
}
}
Also, for future questions, I would recommend posting a Minimal, Complete, and Verifiable example. This way, people are much more willing (and capable) to help. For instance, I had to make assumptions about N_GROUPS and NN. Even with low values such as 100 for NN, the memory consumption would already be so high that it will likely cause problems, but without a MCVE, it's hard to tell.

Answer 2

Instead of having array of some pointer to other arrays of some pointers to other arrays of ....
simply use a pointer to array[nn][nn][nn][nn] of doubles.
Something like:
#define NN 2
#define N_GROUPS 4
int main(int argc, char* argv[])
{
double (*I_object)[NN][NN][NN][NN]; // Define pointer
I_object = calloc(N_GROUPS, sizeof * I_object); // Allocate and zero-init memory
I_object[3][1][1][1][1] = 42; // Use as 5D matrix
printf("%f\n", I_object[3][1][1][1][1]);
free(I_object); // Free memory
return 0;
}